Opening the Strait
The English Channel, a Border Sculpted by Time
Geosite details
100 million years ago, a warm sea covered a large part of Western Europe. In these waters flourished countless microscopic algae with calcium-rich skeletons. When they died, their shells accumulated on the ocean floor, gradually forming thick layers of chalk.
Over the millennia, the movements of the Earth’s crust have shaped a chalk relief linking northern France to London, creating a natural passage between the two territories. This rocky barrier also held back a gigantic glacial lake, born from the melting of glaciers according to climatic variations.
But 450,000 years ago, this lake overflowed in a natural cataclysm: a “mega-flood” dug deep basins in the seabed and submerged the relief that linked France and England. Britain became an island and the Channel Strait was born.
Although very busy today, this area has revealed to scientists geological traces of this spectacular flood. This history, engraved in rock, forever connects France and Britain, explaining their similar landscapes, shared biodiversity and deep cultural ties.